<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <link rel="stylesheet" href="./assets/lib/layui/css/layui.css" />
    <link rel="stylesheet" href="./assets/lib/layui/css/layui.mobile.css" />
    <link rel="stylesheet" href="./assets/css/index_style.css" />
    <link rel="stylesheet" href="./assets/css/login.css" />
  </head>

  <body>
    <div class="header" id="demo">
      <!-- <div class="top_logo"></div> -->
      <!-- <div class="canvaszz"></div> -->

      <canvas id="canvas"></canvas>
    </div>
    <div class="cantainer">
      <h1>大事件后台管理系统</h1>
      <form class="layui-form bot" action="">
        <div class="layui-form-item">
          <i class="layui-icon layui-icon-username q"></i>
          <input
            type="text"
            name="username"
            required
            lay-verify="required"
            placeholder=" 用户名或者邮箱"
            autocomplete="off"
            class="layui-input w"
          />
          <i class="layui-icon layui-icon-password qq"></i>
          <input
            type="password"
            name="password"
            required
            lay-verify="required"
            placeholder="密码"
            autocomplete="off"
            class="layui-input w"
          />
          <button class="layui-btn w" lay-submit lay-filter="formDemo">
            登入
          </button>
        </div>
      </form>
    </div>
    <script>
      //宇宙特效
      "use strict";
      var canvas = document.getElementById("canvas"),
        ctx = canvas.getContext("2d"),
        w = (canvas.width = window.innerWidth),
        h = (canvas.height = window.innerHeight),
        hue = 217,
        stars = [],
        count = 0,
        maxStars = 1300; //星星数量

      var canvas2 = document.createElement("canvas"),
        ctx2 = canvas2.getContext("2d");
      canvas2.width = 100;
      canvas2.height = 100;
      var half = canvas2.width / 2,
        gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
      gradient2.addColorStop(0.025, "#CCC");
      gradient2.addColorStop(0.1, "hsl(" + hue + ", 61%, 33%)");
      gradient2.addColorStop(0.25, "hsl(" + hue + ", 64%, 6%)");
      gradient2.addColorStop(1, "transparent");

      ctx2.fillStyle = gradient2;
      ctx2.beginPath();
      ctx2.arc(half, half, half, 0, Math.PI * 2);
      ctx2.fill();

      // End cache

      function random(min, max) {
        if (arguments.length < 2) {
          max = min;
          min = 0;
        }

        if (min > max) {
          var hold = max;
          max = min;
          min = hold;
        }

        return Math.floor(Math.random() * (max - min + 1)) + min;
      }

      function maxOrbit(x, y) {
        var max = Math.max(x, y),
          diameter = Math.round(Math.sqrt(max * max + max * max));
        return diameter / 2;
        //星星移动范围，值越大范围越小，
      }

      var Star = function () {
        this.orbitRadius = random(maxOrbit(w, h));
        this.radius = random(60, this.orbitRadius) / 8;
        //星星大小
        this.orbitX = w / 2;
        this.orbitY = h / 2;
        this.timePassed = random(0, maxStars);
        this.speed = random(this.orbitRadius) / 50000;
        //星星移动速度
        this.alpha = random(2, 10) / 10;

        count++;
        stars[count] = this;
      };

      Star.prototype.draw = function () {
        var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
          y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
          twinkle = random(10);

        if (twinkle === 1 && this.alpha > 0) {
          this.alpha -= 0.05;
        } else if (twinkle === 2 && this.alpha < 1) {
          this.alpha += 0.05;
        }

        ctx.globalAlpha = this.alpha;
        ctx.drawImage(
          canvas2,
          x - this.radius / 2,
          y - this.radius / 2,
          this.radius,
          this.radius
        );
        this.timePassed += this.speed;
      };

      for (var i = 0; i < maxStars; i++) {
        new Star();
      }

      function animation() {
        ctx.globalCompositeOperation = "source-over";
        ctx.globalAlpha = 0.5; //尾巴
        ctx.fillStyle = "hsla(" + hue + ", 64%, 6%, 2)";
        ctx.fillRect(0, 0, w, h);

        ctx.globalCompositeOperation = "lighter";
        for (var i = 1, l = stars.length; i < l; i++) {
          stars[i].draw();
        }

        window.requestAnimationFrame(animation);
      }

      animation();
    </script>
    <script src="./assets/lib/jquery.js"></script>
    <script src="./assets/lib/jquery.particleground.min.js"></script>
    <script src="./assets/js/common.js"></script>
    <script src="./assets/lib/layui/layui.all.js"></script>
    <script src="./assets/js/login.js"></script>
  </body>
</html>
